Johannes from PuzLogical.com pointed me to a puzzle called MinuPlu which is the same like KenKen (another Sudoku variant).

The rules for Minuplu are almost as simple as Sudoku or KenKen. All cells of a MinuPlu have to be filled in with numbers. The possible numbers range from 1 to the size of the MinuPlu. For example, in a 4×4 MinuPlu there are the numbers 1, 2, 3 and 4. Each number must appear exactly once in each row and each column.

However, in contrast to Sudoku, there are no blocks where this must be fulfilled as well. Each region surrounded by a thick line contains an arithmetic operation (addition, subtraction, multiplication or division) and a result. The numbers in each such region must yield the indicated result when combined by the corresponding operation. Happy Puzzling!